About the author:

1. China Railway First Group Co., Ltd., Xi’an, Shaanxi 710054, China;2. Wuhan Sanyuan Special Building Materials Co., Ltd., Wuhan, Hubei 430083, China

Abstract:

Based on the arch open⁃cut tunnel structure of large open⁃cut high⁃speed railway tunnel, inorder to control the cracks of mass concrete in the side wall, the temperature⁃controlled shrinkage⁃compensating concrete prepared by temperature⁃controlled magnesium oxide expansive agent was used forconstruction. The results showed that the compressive strength of temperature⁃controlled shrinkage⁃compensating concrete was slightly lower than that of reference concrete at 7d, slightly higher at 28d and60d, the setting time was prolonged, and the limiting expansion rate was increased. In the full⁃scalemodel test, the time of the temperature peak of the concrete in the verification section was delayed by 24hcompared with the reference section, the temperature peak was reduced by 5. 5℃, and the maximummicro⁃strain value after temperature correction was increased by 62με. The center temperature rise of themass concrete solid structure of the arch side wall was less than or equal to 29. 0℃, the cooling rate ofthe early age was less than or equal to 5℃/ d, the concrete was in a micro⁃expansion state for a longtime, and the risk of shrinkage cracking was small. The temperature⁃controlled shrinkage⁃compensatingconcrete prepared by the temperature⁃controlled magnesium oxide expansive agent has achieved goodcrack control effect in the mass concrete structure.